Study Flashcards

Question: Is endianness related to the order of bytes in a numeric data type?

Answer: True

Question: What is the main difference between Little Endian and Big Endian order?

The order of bits in a byte
The order of bytes in a numeric data type
The size of the data type

Answer: The order of bytes in a numeric data type

Question: __________ is the least significant byte of a number in Little Endian order.

Answer: The most significant byte

Question: Explain the difference between Little Endian and Big Endian order in terms of byte storage.

Answer: In Little Endian, the least significant byte is stored at the lowest address, while in Big Endian, the most significant byte is stored at the lowest address.

Question: Is endian ordering important for embedded programmers and device driver programmers?

Answer: True

Question: What is the purpose of a Hardware Abstraction Layer (HAL) in cross platform code?

To manage memory fragmentation
To map IO onto main memory
To provide a consistent interface to hardware

Answer: To provide a consistent interface to hardware

Question: The width of the __________ determines the addressing range in a system.

Answer: address bus

Question: Explain the purpose of the BSS segment in memory allocation.

Answer: The BSS segment is used for non explicitly initialized data in embedded systems.

Question: In ARM, is it recommended to call library functions in an interrupt handler?

Answer: False

Question: What is the main purpose of interrupt handlers in ARM?

To execute long running operations
To handle burst of data quickly
To halt all processing on the CPU

Answer: To handle burst of data quickly

Question: __________ is the register in ARM that holds the function return value.

Answer: R0

Question: Explain the ARM Procedure Call Standard for parameter passing.

Answer: The first four parameters are passed in registers R0-R3, and subsequent parameters are passed on the stack. The return value is expected in R0.

Question: In ARM, should registers R0-R3 be preserved in a function call?

Answer: False

Question: What is the purpose of preserving registers in ARM function calls?

To avoid trashing important data
To maintain the contract between the caller and the callee functions
To slow down the execution speed

Answer: To maintain the contract between the caller and the callee functions

Question: GNU ARM Assembly makes it easy to push and pop registers using the _________ instruction.

Answer: push/pop

Question: Explain the contract between the caller and the callee functions in ARM regarding register usage.

Answer: The caller expects R0-R3 to be overwritten, but R4 and up to be left alone. The callee can use R0-R3 freely but must preserve R4 and up.

Question: In ARM, the callER function must preserve all registers used, including R0-R3.

Answer: False

Question: What is the purpose of the LR (link register) in ARM function calls?

To hold the return value of the function
To store the address to return to after the function call
To manage the stack pointer

Answer: To store the address to return to after the function call

Question: In ARM Basics, is it correct that the code snippet pushes registers r4-r7 and lr onto the stack?

Answer: True

Question: What is the purpose of the bx lr instruction in ARM Function Structure?

To branch to a different address
To return from the function
To load a register with a value

Answer: To return from the function

Question: __________ is an absolute convention in ARM Function Structure to preserve registers before doing work in the function.

Answer: push {r4-r7, lr}

Question: Describe why following conventions and standards in ARM programming is important.

Answer: Following conventions and standards ensures code consistency, readability, and helps prevent bugs that may be hard to troubleshoot.